This invention relates to a process for the separation of gaseous and/or liquid mixtures, and in particular to a system incorporating a cooling step which leads to the formation of separable phases having different densities, and which is especially applicable to the treatment of sour gases.
The separation of sour gases, understood to mean essentially CO.sub.2, H.sub.2 S, and mercaptans, is a process step that is frequently necessary in the processing of raw gas streams. Of such sour gas species which must be isolated from downstream facilities due to their corrosive and catalyst-damaging properties, CO.sub.2 and H.sub.2 S occur most frequently, and generally in significant concentrations, e.g., in natural gas or cracked gases. Removal of the sour gases can be conducted in various ways. Absorption methods--of a chemical as well as physical nature--have proven to be extremely effective. The scrubbing steps are usually conducted in such a way that the solvent, loaded with the sour gases, is regenerated and reused. In order to keep the efficiency of the scrubbing process at a maximum, regeneration must be performed usually up to an almost complete separation of the sour gases from the solvent. As a result, substantial costs are associated with the heating and recycling of the solvent a well as for make-up solvent. Furthermore, a large in-process and storage inventory of the solvent is a significant economic factor, especially where the solvent is expensive.
Distillation methods are also employed for separating the mixtures that consist mostly of methane, lower hydrocarbons and the sour gases. However, problems are encountered in many cases in these methods in the freezing out of the sour gas components.